[Plugin: RSS Feed Checker] Custom modifications to 0.8

* Plugin URI goes to plugin site
* renderlinks() and rss_list() take an $instance object instead of $count
* rss_list() can filter by link category if $instance[‘title’] is a category name
* rss_list() may have no limit if $count==0
* rss_list() will return results that have no associated RSS, and renderlinks() will produce only the titles for these results
* renderlinks() will show the link_image if it exists
* The widget form() admin ui will present a datalist of link category names that can be used for the title.
* “Show all links” no longer displays if the blogroll page does not exist. It had linked to the automated Hello World post because its id=0.

Other changes that got left out of the diff:
* Added ul class “xoxo” to be like core links
* Added aside class “widget_links” to be like core links
* I also removed the margin-bottom for .blogrollitem from my CSS because my
site did not seem to need it and this made the cluster of links without RSS feeds look like core links, but YMMV.

Quick fixes for that code I posted:
* In renderlinks, in the final htmlout, change “%s %s” to “%s%s” and up earlier add a space to the end of the $image_html sprintf.
* also at $image_html, style=”blogrollicon” should be class.
* Add to CSS: .RSSFeedBlogRoll img.blogrollicon { width: 16px; height: 16px; } because some sites present large favicons.

Also, I wrote some hacky favicon/RSS feed discovery code which needs a rewrite by someone who knows how to code for WordPress: http://pastebin.com/GWuinzEg